1. Field of the Invention
The present invention relates to a clasp device for accessories such as necklaces, bracelets and anklets.
2. Prior Art
Many different Clasp devices have been proposed for utilizing with a various accessories. One example of a conventional clasp device is disclosed in Japanese Laid-open Utility Model Publication No. 7-30730. As shown in FIGS. 14(a) to (c), the clasp device includes a clasp 22 and a locking pin 23 as a locking element. The locking pin 23 has a rounded forward end for facilitating insertion thereof and a locking groove 23a provided peripherally of the locking pin 23 at a position proximate to the rounded forward end. The clasp 22 comprises: a positioning casing 24 for positioning a various assembly parts; a receiving member 25 in the form of a hollow tube for receiving therein the locking pin 23; a stopper member 26 having a center opening for receiving the receiving member 25 and movable into the inner region of the receiving member 25; a coil spring 27a accommodated in a spring case 27 for urging the stopper member 26 outwardly from the clasp 22; and a cover lid 28 into which the positioning casing 24 is fitted. As best seen in FIGS. 14(a) and (c), the stopper member 26 consists of a generally U-shaped plate 26a and a push button 26b, defining therein a center opening for receiving the receiving member 25. The stopper member 26 is supported at its bottom by the coil spring 27a within the spring case 27, thereby urged upward by resilient action of the coil spring 27a. The receiving member 25 is halfway inserted into the stopper member 26 through the center opening of the stopper member 26. To this end, at the inserted portion of the receiving member 25, thickness of the tubular cross section is partly reduced to have the outer width corresponding to the inner width of the U-shaped plate 26a. The receiving member 25 is provided with an engaging opening, which is engaged with the inner lower end 26c of the stopper member 26 upon insertion of the receiving member through the center opening of the stopper member 26. As shown in FIG. 14(c), since the stopper member 26 is urged upward by the coil spring 27a, the inner lower end 26c of the stopper member 26 extends inwardly through the engaging opening into the inner region of the receiving member 25.
When the locking pin 23 is inserted into the clasp 22 though the insertion opening communicating with the receiving member 25, the stopper member 26 is depressed against the resilient action of the coil spring 27a with its inner lower end 26c depressed by the peripheral surface of the locking pin 23, and in a position where the rounded forward end of the locking pin 23 has passed the inner lower end 26c, the stopper member 26 is again urged upward and its inner lower end 26c engages with the locking groove 23a of the locking pin 23.
Disengagement of the clasp device is accomplished by pulling out the locking pin 23 while depressing the push button 26b against the resilient action of the coil spring 27a.
In such clasp device, when assembled, the clasp 22, the receiving member 25, the stopper member 26 and the spring case 27 accommodating the coil spring 27a are assembled with the cover lid 28. However, since the coil spring 27a is to be accommodated in the spring case 27, brazing of the receiving member 25 and the spring case 27 would result in deterioration of the coil spring 27a due to heat generated during the brazing operation. Therefore, the stopper member 26 and the spring case 27 should be assembled with the cover lid 28 by finger operation or by the use of a tweezers. For this reason, as shown in FIG. 14(d), the upper surface of the spring case 27 is formed to have an arcuate surface corresponding to the peripheral surface of the receiving member 25 and a pair of protrusions so as to facilitate positioning of the receiving member 25. However, since the size of the protrusions are restricted in a small clasp, engagement of the receiving member 25 and the spring case 27 is very much likely to come off. This makes the whole assembly difficult and time-consuming.
Also, since the clasp 22 includes the spring case 27 at the lower end of the cover lid 28, size of the clasp becomes larger.
Further, since the receiving member 25 is provided with an engaging groove for the engagement with the protrusions of the spring case 27, and the positioning casing 24 is provided with a cut-out for positioning the spring case 27, the number of working processes is increasing. This also leads to increasing number of assembly processes as well as increment in cost.
With the foregoing difficulties of the prior art clasp device in view, the present invention seeks to provide a clasp device comprising reduced number of assembly parts, which contributes to reduced cost and facilitating the assembly thereof The present invention also seeks to provide a small-sized clasp device for accessories.